Isle of Man plate check site here - https://services.gov.im/vehicles-driving/vehicle-search/

Not roadtested enough to be a recommendation - only one film tried, and some of them work, but others don't. I don't have a grip on how the IoM system works, but I think it's a mix of sequential series within which old plates can be recycled - so something like a hybrid of UK and HK (for instance) practices. Also noted that some of the plates with hits in that film give younger IoM plate dates than the car if they were originally UK mainland reg'd and imported used - but it also helpfully gives the initial UK plate.